From c79cc4845411209b7ce143ebc4f98adfd969b2b2 Mon Sep 17 00:00:00 2001 From: yff-1996 Date: Tue, 15 Jun 2021 16:19:01 +0800 Subject: [PATCH 01/12] =?UTF-8?q?=E6=B7=BB=E5=8A=A00151.=E7=BF=BB=E8=BD=AC?= =?UTF-8?q?=E5=AD=97=E7=AC=A6=E4=B8=B2=E9=87=8C=E7=9A=84=E5=8D=95=E8=AF=8D?= =?UTF-8?q?=20Python=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0151.翻转字符串里的单词.md | 51 ++++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/problems/0151.翻转字符串里的单词.md b/problems/0151.翻转字符串里的单词.md index d76734e4..a174d550 100644 --- a/problems/0151.翻转字符串里的单词.md +++ b/problems/0151.翻转字符串里的单词.md @@ -318,6 +318,57 @@ class Solution { Python： +```Python3 +class Solution: + #1.去除多余的空格 + def trim_spaces(self,s): + n=len(s) + left=0 + right=n-1 + + while left<=right and s[left]==' ': #去除开头的空格 + left+=1 + while left<=right and s[right]==' ': #去除结尾的空格 + right=right-1 + tmp=[] + while left<=right: #去除单词中间多余的空格 + if s[left]!=' ': + tmp.append(s[left]) + elif tmp[-1]!=' ': #当前位置是空格，但是相邻的上一个位置不是空格，则该空格是合理的 + tmp.append(s[left]) + left+=1 + return tmp +#2.翻转字符数组 + def reverse_string(self,nums,left,right): + while left Date: Tue, 15 Jun 2021 18:42:59 +0800 Subject: [PATCH 02/12] =?UTF-8?q?=E6=B7=BB=E5=8A=A0151.=E7=BF=BB=E8=BD=AC?= =?UTF-8?q?=E5=AD=97=E7=AC=A6=E4=B8=B2=E9=87=8C=E7=9A=84=E5=8D=95=E8=AF=8D?= =?UTF-8?q?=20python=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0151.翻转字符串里的单词.md | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/problems/0151.翻转字符串里的单词.md b/problems/0151.翻转字符串里的单词.md index a174d550..c76ff0e1 100644 --- a/problems/0151.翻转字符串里的单词.md +++ b/problems/0151.翻转字符串里的单词.md @@ -359,10 +359,10 @@ class Solution: return None #4.翻转字符串里的单词 - def reverseWords(self, s): #测试用例："the sky is blue - l = self.trim_spaces(s) #输出："the sky is blue" - self.reverse_string( l, 0, len(l) - 1) #输出："blue is sky the" - self.reverse_each_word(l) #输出："blue is sky the" + def reverseWords(self, s): #测试用例："the sky is blue" + l = self.trim_spaces(s) #输出：['t', 'h', 'e', ' ', 's', 'k', 'y', ' ', 'i', 's', ' ', 'b', 'l', 'u', 'e' + self.reverse_string( l, 0, len(l) - 1) #输出：['e', 'u', 'l', 'b', ' ', 's', 'i', ' ', 'y', 'k', 's', ' ', 'e', 'h', 't'] + self.reverse_each_word(l) #输出：['b', 'l', 'u', 'e', ' ', 'i', 's', ' ', 's', 'k', 'y', ' ', 't', 'h', 'e'] return ''.join(l) #输出：blue is sky the From 1ad27bcb0d5bba938a5e27ce5c12ebb4eda9a81e Mon Sep 17 00:00:00 2001 From: callmePicacho <38685653+callmePicacho@users.noreply.github.com> Date: Wed, 16 Jun 2021 07:55:38 +0800 Subject: [PATCH 03/12] =?UTF-8?q?=E4=B8=BA"=E6=BB=91=E5=8A=A8=E7=AA=97?= =?UTF-8?q?=E5=8F=A3"=E7=B3=BB=E5=88=97=E7=9B=B8=E5=85=B3=E9=A2=98?= =?UTF-8?q?=E7=9B=AE=E6=8E=A8=E8=8D=90=E6=B7=BB=E5=8A=A0=E9=93=BE=E6=8E=A5?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0209.长度最小的子数组.md | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/problems/0209.长度最小的子数组.md b/problems/0209.长度最小的子数组.md index 90280451..42687514 100644 --- a/problems/0209.长度最小的子数组.md +++ b/problems/0209.长度最小的子数组.md @@ -109,7 +109,7 @@ public: }; ``` -时间复杂度：$O(n)$ +时间复杂度：$O(n)$ 空间复杂度：$O(1)$ **一些录友会疑惑为什么时间复杂度是O(n)**。 @@ -118,8 +118,8 @@ public: ## 相关题目推荐 -* 904.水果成篮 -* 76.最小覆盖子串 +* [904.水果成篮](https://leetcode-cn.com/problems/fruit-into-baskets/) +* [76.最小覆盖子串](https://leetcode-cn.com/problems/minimum-window-substring/) From 0bafb2d775466d18eec6b142163657ffe3a66b05 Mon Sep 17 00:00:00 2001 From: Kelvin Date: Tue, 15 Jun 2021 21:05:09 -0400 Subject: [PATCH 04/12] =?UTF-8?q?=E6=9B=B4=E6=94=B9=20=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2.md?= =?UTF-8?q?=20Java=20=E4=BB=A3=E7=A0=81=E6=A0=BC=E5=BC=8F.?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/背包理论基础01背包-2.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/背包理论基础01背包-2.md b/problems/背包理论基础01背包-2.md index e85d31b4..075bb5b1 100644 --- a/problems/背包理论基础01背包-2.md +++ b/problems/背包理论基础01背包-2.md @@ -214,7 +214,7 @@ int main() { Java： ```java - public static void main(String[] args) { + public static void main(String[] args) { int[] weight = {1, 3, 4}; int[] value = {15, 20, 30}; int bagWight = 4; From ecd98c9a79e1e3efbde2dc140d9adc7b2af93c3b Mon Sep 17 00:00:00 2001 From: Kelvin Date: Tue, 15 Jun 2021 21:06:42 -0400 Subject: [PATCH 05/12] =?UTF-8?q?=E5=A2=9E=E5=8A=A0=20=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2.md?= =?UTF-8?q?=20Python3=20=E5=AE=9E=E7=8E=B0=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/背包理论基础01背包-2.md | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/problems/背包理论基础01背包-2.md b/problems/背包理论基础01背包-2.md index 075bb5b1..aee1a929 100644 --- a/problems/背包理论基础01背包-2.md +++ b/problems/背包理论基础01背包-2.md @@ -242,7 +242,24 @@ Java： Python： +```python +def test_1_wei_bag_problem(): + weight = [1, 3, 4] + value = [15, 20, 30] + bag_weight = 4 + # 初始化: 全为0 + dp = [0] * (bag_weight + 1) + # 先遍历物品, 再遍历背包容量 + for i in range(len(weight)): + for j in range(bag_weight, weight[i] - 1, -1): + # 递归公式 + dp[j] = max(dp[j], dp[j - weight[i]] + value[i]) + + print(dp) + +test_1_wei_bag_problem() +``` Go： ```go From 5dc2a0b745086c026e75cde53d898a67f9e98eb1 Mon Sep 17 00:00:00 2001 From: Kelvin Date: Tue, 15 Jun 2021 21:09:06 -0400 Subject: [PATCH 06/12] =?UTF-8?q?=E6=9B=B4=E6=94=B9=20=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2.md?= =?UTF-8?q?=20=E6=A0=BC=E5=BC=8F?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 增加一个空行, 因为如果没有空行浏览器render文字就会有问题. --- problems/背包理论基础01背包-2.md | 1 + 1 file changed, 1 insertion(+) diff --git a/problems/背包理论基础01背包-2.md b/problems/背包理论基础01背包-2.md index aee1a929..c8b80655 100644 --- a/problems/背包理论基础01背包-2.md +++ b/problems/背包理论基础01背包-2.md @@ -5,6 +5,7 @@

欢迎大家参与本项目，贡献其他语言版本的代码，拥抱开源，让更多学习算法的小伙伴们收益！

+ # 动态规划：关于01背包问题，你该了解这些！（滚动数组） 昨天[动态规划：关于01背包问题，你该了解这些！](https://mp.weixin.qq.com/s/FwIiPPmR18_AJO5eiidT6w)中是用二维dp数组来讲解01背包。 From 3746acd22b02e94945a20d9c2a69de788a0f016c Mon Sep 17 00:00:00 2001 From: Kelvin Date: Tue, 15 Jun 2021 21:10:08 -0400 Subject: [PATCH 07/12] =?UTF-8?q?=E6=9B=B4=E6=96=B0=20=E8=83=8C=E5=8C=85?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=8001=E8=83=8C=E5=8C=85-2.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 小typo. --- problems/背包理论基础01背包-2.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/背包理论基础01背包-2.md b/problems/背包理论基础01背包-2.md index c8b80655..48275908 100644 --- a/problems/背包理论基础01背包-2.md +++ b/problems/背包理论基础01背包-2.md @@ -36,7 +36,7 @@ **其实可以发现如果把dp[i - 1]那一层拷贝到dp[i]上，表达式完全可以是：dp[i][j] = max(dp[i][j], dp[i][j - weight[i]] + value[i]);** -**于其把dp[i - 1]这一层拷贝到dp[i]上，不如只用一个一维数组了**，只用dp[j]（一维数组，也可以理解是一个滚动数组）。 +**与其把dp[i - 1]这一层拷贝到dp[i]上，不如只用一个一维数组了**，只用dp[j]（一维数组，也可以理解是一个滚动数组）。 这就是滚动数组的由来，需要满足的条件是上一层可以重复利用，直接拷贝到当前层。 From a7d9d7aa23d2bb1d647d758b3ea1d65aef8e28e6 Mon Sep 17 00:00:00 2001 From: kok-s0s <2694308562@qq.com> Date: Wed, 16 Jun 2021 09:39:16 +0800 Subject: [PATCH 08/12] =?UTF-8?q?=E6=8F=90=E4=BA=A4=20=E3=80=8A=E4=BB=8E?= =?UTF-8?q?=E5=89=8D=E5=BA=8F=E4=B8=8E=E4=B8=AD=E5=BA=8F=E9=81=8D=E5=8E=86?= =?UTF-8?q?=E5=BA=8F=E5=88=97=E6=9E=84=E9=80=A0=E4=BA=8C=E5=8F=89=E6=A0=91?= =?UTF-8?q?=E3=80=8BJavaScript=E7=89=88=E6=9C=AC=E7=9A=84=E4=BB=A3?= =?UTF-8?q?=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...中序与后序遍历序列构造二叉树.md | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/problems/0106.从中序与后序遍历序列构造二叉树.md b/problems/0106.从中序与后序遍历序列构造二叉树.md index 600a38e0..4c5a70a0 100644 --- a/problems/0106.从中序与后序遍历序列构造二叉树.md +++ b/problems/0106.从中序与后序遍历序列构造二叉树.md @@ -775,6 +775,20 @@ var buildTree = function(inorder, postorder) { }; ``` +从前序与中序遍历序列构造二叉树 + +```javascript +var buildTree = function(preorder, inorder) { + if(!preorder.length) + return null; + let root = new TreeNode(preorder[0]); + let mid = inorder.findIndex((number) => number === root.val); + root.left = buildTree(preorder.slice(1, mid + 1), inorder.slice(0, mid)); + root.right = buildTree(preorder.slice(mid + 1, preorder.length), inorder.slice(mid + 1, inorder.length)); + return root; +}; +``` + ----------------------- * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) * B站视频：[代码随想录](https://space.bilibili.com/525438321) From d5b0e0ce587df7bb9c627bbad784b71d01098e36 Mon Sep 17 00:00:00 2001 From: Jijie LIU Date: Wed, 16 Jun 2021 14:49:07 +0200 Subject: [PATCH 09/12] =?UTF-8?q?Update=2093.=E5=A4=8D=E5=8E=9FIP=E5=9C=B0?= =?UTF-8?q?=E5=9D=80,=20=E6=B7=BB=E5=8A=A0Python3=E7=89=88=E6=9C=AC?= =?UTF-8?q?=EF=BC=8C=E7=94=A8=E4=BA=86=E6=96=B0=E7=9A=84=E5=89=AA=E6=9E=9D?= =?UTF-8?q?=E6=96=B9=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0093.复原IP地址.md | 40 +++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/problems/0093.复原IP地址.md b/problems/0093.复原IP地址.md index a8b9a215..c47896d9 100644 --- a/problems/0093.复原IP地址.md +++ b/problems/0093.复原IP地址.md @@ -338,6 +338,46 @@ class Solution(object): return ans``` ``` +```python3 +class Solution: + def __init__(self) -> None: + self.s = "" + self.res = [] + + def isVaild(self, s: str) -> bool: + if len(s) > 1 and s[0] == "0": + return False + + if 0 <= int(s) <= 255: + return True + + return False + + def backTrack(self, path: List[str], start: int) -> None: + if start == len(self.s) and len(path) == 4: + self.res.append(".".join(path)) + return + + for end in range(start + 1, len(self.s) + 1): + # 剪枝 + # 保证切割完，s没有剩余的字符。 + if len(self.s) - end > 3 * (4 - len(path) - 1): + continue + if self.isVaild(self.s[start:end]): + # 在参数处，更新状态，实则创建一个新的变量 + # 不会影响当前的状态，当前的path变量没有改变 + # 因此递归完不用path.pop() + self.backTrack(path + [self.s[start:end]], end) + + def restoreIpAddresses(self, s: str) -> List[str]: + # prune + if len(s) > 3 * 4: + return [] + self.s = s + self.backTrack([], 0) + return self.res +``` + JavaScript： ```js From 78b32e8c6c2c7708e1407c729ceebfeeca033f4d Mon Sep 17 00:00:00 2001 From: KailokFung Date: Thu, 17 Jun 2021 17:53:56 +0800 Subject: [PATCH 10/12] =?UTF-8?q?feat(0541):=20=E5=A2=9E=E5=8A=A0=E5=8F=A6?= =?UTF-8?q?=E4=B8=80=E7=A7=8DJava=E7=89=88=E6=9C=AC=E5=86=99=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0541.反转字符串II.md | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/problems/0541.反转字符串II.md b/problems/0541.反转字符串II.md index 00581fc0..4b3ed43b 100644 --- a/problems/0541.反转字符串II.md +++ b/problems/0541.反转字符串II.md @@ -103,6 +103,7 @@ public: Java： ```Java +//解法一 class Solution { public String reverseStr(String s, int k) { StringBuffer res = new StringBuffer(); @@ -128,6 +129,28 @@ class Solution { return res.toString(); } } + +//解法二（似乎更容易理解点） +//题目的意思其实概括为 每隔2k个反转前k个，尾数不够k个时候全部反转 +class Solution { + public String reverseStr(String s, int k) { + char[] ch = s.toCharArray(); + for(int i = 0; i < ch.length; i += 2 * k){ + int start = i; + //这里是判断尾数够不够k个来取决end指针的位置 + int end = Math.min(ch.length - 1, start + k - 1); + //用异或运算反转 + while(start < end){ + ch[start] ^= ch[end]; + ch[end] ^= ch[start]; + ch[start] ^= ch[end]; + start++; + end--; + } + } + return new String(ch); + } +} ``` Python： From 928b034e9bca9667949e22b589ece1b6f0b7a4d0 Mon Sep 17 00:00:00 2001 From: Jijie LIU Date: Thu, 17 Jun 2021 17:27:30 +0200 Subject: [PATCH 11/12] =?UTF-8?q?update=2037.=20=E8=A7=A3=E6=95=B0?= =?UTF-8?q?=E7=8B=AC:=20=E6=8F=90=E4=BE=9Bpython3=20=E7=89=88=E6=9C=AC?= =?UTF-8?q?=EF=BC=8C=E7=AE=80=E5=8C=96isValid=EF=BC=8C=20=E6=8F=90?= =?UTF-8?q?=E9=AB=98=E5=9B=9E=E6=BA=AF=E5=87=BD=E6=95=B0=E7=9A=84=E5=8F=AF?= =?UTF-8?q?=E8=AF=BB=E6=80=A7?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0037.解数独.md | 53 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/problems/0037.解数独.md b/problems/0037.解数独.md index 4eb60704..e43708b8 100644 --- a/problems/0037.解数独.md +++ b/problems/0037.解数独.md @@ -321,6 +321,59 @@ class Solution: backtrack(board) ``` +Python3: + +```python3 +class Solution: + def __init__(self) -> None: + self.board = [] + + def isValid(self, row: int, col: int, target: int) -> bool: + for idx in range(len(self.board)): + # 同列是否重复 + if self.board[idx][col] == str(target): + return False + # 同行是否重复 + if self.board[row][idx] == str(target): + return False + # 9宫格里是否重复 + box_row, box_col = (row // 3) * 3 + idx // 3, (col // 3) * 3 + idx % 3 + if self.board[box_row][box_col] == str(target): + return False + return True + + def getPlace(self) -> List[int]: + for row in range(len(self.board)): + for col in range(len(self.board)): + if self.board[row][col] == ".": + return [row, col] + return [-1, -1] + + def isSolved(self) -> bool: + row, col = self.getPlace() # 找个空位置 + + if row == -1 and col == -1: # 没有空位置，棋盘被填满的 + return True + + for i in range(1, 10): + if self.isValid(row, col, i): # 检查这个空位置放i，是否合适 + self.board[row][col] = str(i) # 放i + if self.isSolved(): # 合适，立刻返回, 填下一个空位置。 + return True + self.board[row][col] = "." # 不合适，回溯 + + return False # 空位置没法解决 + + def solveSudoku(self, board: List[List[str]]) -> None: + """ + Do not return anything, modify board in-place instead. + """ + if board is None or len(board) == 0: + return + self.board = board + self.isSolved() +``` + Go： Javascript: From d6ab48534d80a506b0e60df8196c9b5e2c802b10 Mon Sep 17 00:00:00 2001 From: kok-s0s <2694308562@qq.com> Date: Sat, 19 Jun 2021 22:16:42 +0800 Subject: [PATCH 12/12] =?UTF-8?q?=E6=9C=80=E5=A4=A7=E4=BA=8C=E5=8F=89?= =?UTF-8?q?=E6=A0=91JavaScript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0654.最大二叉树.md | 36 ++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/problems/0654.最大二叉树.md b/problems/0654.最大二叉树.md index f0d3e594..4e1e7a72 100644 --- a/problems/0654.最大二叉树.md +++ b/problems/0654.最大二叉树.md @@ -311,6 +311,42 @@ func findMax(nums []int) (index int){ } ``` +JavaScript版本 + +```javascript +/** + * Definition for a binary tree node. + * function TreeNode(val, left, right) { + * this.val = (val===undefined ? 0 : val) + * this.left = (left===undefined ? null : left) + * this.right = (right===undefined ? null : right) + * } + */ +/** + * @param {number[]} nums + * @return {TreeNode} + */ +var constructMaximumBinaryTree = function (nums) { + const BuildTree = (arr, left, right) => { + if (left > right) + return null; + let maxValue = -1; + let maxIndex = -1; + for (let i = left; i <= right; ++i) { + if (arr[i] > maxValue) { + maxValue = arr[i]; + maxIndex = i; + } + } + let root = new TreeNode(maxValue); + root.left = BuildTree(arr, left, maxIndex - 1); + root.right = BuildTree(arr, maxIndex + 1, right); + return root; + } + let root = BuildTree(nums, 0, nums.length - 1); + return root; +}; +```